a. Field of the Invention
The present disclosure relates to monitoring of therapeutic procedures. In particular, the present disclosure relates to apparatus and methods for monitoring and displaying lesion formation during therapeutic procedures, such as cardiac ablation procedures utilized in the treatment of cardiac arrhythmia.
b. Background Art
It is well known that atrial fibrillation results from disorganized electrical activity in the heart muscle (the myocardium). The surgical maze procedure has been developed for treating atrial fibrillation, and involves the creation of a series of surgical incisions through the atrial myocardium in a preselected pattern so as to create conductive corridors of viable tissue bounded by scar tissue.
As an alternative to the surgical incisions of the maze procedure, transmural ablations of the heart may be used. Such ablations may be performed from within the chambers of the heart (endocardial ablation), using endovascular devices (e.g., catheters) introduced through arteries or veins. Various ablation techniques may be used, including, but not limited to, cryogenic ablation, radiofrequency ablation, laser ablation, ultrasonic ablation, and microwave ablation. The ablation devices are used to create elongated transmural lesions—that is, lesions extending through a sufficient thickness of the myocardium to block electrical conduction—forming the boundaries of the conductive corridors in the atrial myocardium. Perhaps most advantageous about the use of transmural ablation rather than surgical incision is the ability to perform ablation procedures without first establishing cardiopulmonary bypass (CPB).
Ablation devices are commonly used in conjunction with diagnostic systems that aid the practitioner in navigating, positioning and orienting the ablation device. These systems can provide a visual reference, such as a three dimensional model or two dimensional image, allowing the physician to more easily determine the orientation of the ablation device relative to the target anatomy. Intracardiac echo (ICE) catheters are one commonly used diagnostic tool that provides a two dimensional image of both therapeutic catheters and cardiac anatomy.
It is desirable for the practitioner (e.g., the doctor or electrophysiologist) to be able to monitor local temperature changes at the ablation site to allow the practitioner to more readily judge the extent of lesion formation during ablation procedures.